Adsorbent coating compositions, laminates and adsorber elements comprising such compositions and methods for their manufacture and use

ABSTRACT

Using zeolites as the active adsorbent, adsorbent laminates have been fabricated with various sheet supports. These adsorbent laminates have been successfully operated for oxygen enrichment at high PSA cycle frequencies, such as upwards of at least 150 cycles per minute. Methods for making suitable adsorbent laminates are described. The methods generally involve forming a slurry comprising a liquid suspending agent, an adsorbent and a binder. Laminates are made by applying the slurry to support material or admixing support material with the slurry. The slurry can be applied to support material using a variety of techniques, including roll coaters, split roll coaters, electrophoretic deposition, etc. One method for making laminates by mixing support material with the adsorbent slurry comprises depositing the slurry onto a foraminous wire, draining the slurry material, and pressing the material to form a ceramic adsorbent paper. Spacers can be formed on adsorbent laminates to space one laminate from another. The spacer dimensions can be uniform, or can vary along a laminate, such as increasing in height from a first end to a second end of the laminate. Gas flow-through apertures also can be formed on laminates. The laminates are adjacent one another to define flow channel between adjacent bodies, whereby a portion of a gas flowing through the flow channels flows through the apertures to facilitate pressure equalization in the adsorbent structure.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of the earlier filing datesof U.S. provisional patent applications, Nos. 60/260,077, 60/261,548 and60/285,527, each of which is incorporated herein by reference.

FIELD

[0002] The present invention concerns laminates and adsorber elementsthat are useful for pressure swing adsorption processes.

BACKGROUND

[0003] Gas separation can be accomplished by flowing a mixture of gasesover an adsorbent that preferentially adsorbs a more readily adsorbedcomponent relative to a less readily adsorbed component of the mixture.Examples of such processes include temperature swing adsorption (TSA)and pressure swing adsorption (PSA). Pressure swing adsorption generallyinvolves coordinated pressure cycling of a gaseous mixture over anadsorbent material. The total pressure is elevated during intervals offlow in a first direction through the adsorbent bed, and is reducedduring intervals of flow in the reverse direction. As the cycle isrepeated, the less readily adsorbed component is concentrated in thefirst direction, while the more readily adsorbed component isconcentrated in the reverse direction.

[0004] In early work in this field, Milton's U.S. Patent Nos. 2,882,243and 2,882,244 described the preparation of type A and type X zeolites,and the use of these materials to separate components of gas mixtures.Other workers in the field recognized the importance of using zeoliteshaving small and uniformly sized crystals as adsorbents for gasseparation processes. Kostinko's U.S. Pat. No. 4,443,422 describes azeolite A having an average particle size of less than 1.7 microns and azeolite X having an average particle size of less than 2.2 microns, andfurther provides a detailed summary of the patent literature in thefield of zeolite preparation.

[0005] Commercial gas separation and chemical gas reactor devicestypically use a granular or pelletized form to hold the crystals incontact with the fluid flow. In many cases, additional benefits arerealized by reducing the containment vessel volume, weight, cost,pressure drop and increasing robustness. A reduction in the volume willincrease fluid velocities, which increases fluid forces on the adsorbentparticles, increases fluid pressure drop across the length of thedevice, and also reduces the time available for mass transfer betweenthe fluid and the adsorbent.

[0006] Hence, a need developed for rigid, low fluid resistance,high-surface-area adsorbent supports that overcome the limitations ofgranular adsorbent beds.

[0007] Supported adsorbent materials are known for use with TSAprocesses. For example, corrugated materials having adsorbent materialapplied thereto are known for use with TSA processes. Rigid,high-surface-area adsorbent structures, such as stacked or spirallywound adsorbent-impregnated sheet material, also are known for use inPSA devices operating at relatively low cycle frequencies. Examples ofsuch adsorbent structures are disclosed in Keefer's U.S. Pat. Nos.4,702,903, 4,801,308 and 5,082,473, which are incorporated herein byreference. Keefer's U.S. Pat. No. 4,801,308 discloses a PSA apparatushaving an adsorbent structure comprising adsorbent sheets. Adsorbentsheets also may be adapted for use in rotary type pressure swingadsorbers. Keefer et al.'s U.S. Pat. No. 6,051,050, for example, whichis incorporated herein by reference, discloses a rotating pressure swingadsorption apparatus comprising a rotor adapted to receive a pluralityof circumferentially spaced adsorbent structures, each of whichcomprises multiple adsorbent sheets.

[0008] As outlined in U.S. Pat. No. 5,082,473, gas separation bypressure swing adsorption (PSA) is advantageously conducted usinglaminated, parallel passage adsorbers. These “adsorbent laminate”adsorbers provide high surface area and relatively low-pressure drop.Thin adsorbent sheets are separated by spacers which establish the gapheight between adjacent sheets and thus define flow channels betweeneach pair of adjacent sheets.

SUMMARY

[0009] As PSA processes evolve, the need for compact devices, anddevices which operate at cycle frequencies considerably higher thancurrently used for commercial applications, has increased. It has becomeapparent that known adsorbent structures are inadequate. For example,compact devices, such as may be used for medical oxygen production,require adsorbent structures considerably reduced in weight relative toknown structures. These compact devices also must be capable of highproductivity and efficiency while producing an acceptably pure gas. Ifthere is too much channel inconsistency, then productivity and gaspurity are comprised. If one flow channel is larger than an adjacent gasflow channel, then premature product break through may occur, whichreduces the purity of the product gas to unacceptable purity levels.Moreover, devices operating at cycle frequencies greater than 50 cyclesper minute require greater flow channel uniformity and less pressuredrop than has heretofore been required. If too much pressure drop occursacross the bed, then higher cycle frequencies, such as on the order ofgreater than 100 cycles per minute (cpm), are not readily achieved. Ascycle frequencies steadily increase the need for new adsorbentstructures capable of operating at these higher frequencies alsoincreases.

[0010] High performance adsorbent laminates must be manufactured withhigh precision so that flow channels between adsorbent layers areuniform in thickness. This helps maintain narrow concentration fronts,so that high product productivity and recovery can be achieved at highpurity. Hence, both the thickness of the applied adsorbent layer on thesupport, and the height of the spacers defining the channels, must beestablished with high accuracy and consistency. The present inventionprovides adsorbent laminate configurations achieving the necessaryaccuracy.

[0011] Using zeolites as the active adsorbent, adsorbent laminates havebeen fabricated with various sheet supports. These adsorbent laminateshave been successfully operated for oxygen enrichment at high PSA cyclefrequencies, such as at 10 cycles per minute or greater, generallygreater than 50 cycles per minute, preferably at least 150 cycles perminute, more preferably 200 cycles per minute, and even more preferablyapproaching 300 cycles per minute or greater.

[0012] Methods for making suitable adsorbent laminates for highfrequency PSA processes are described. The methods generally involveforming a slurry comprising a liquid suspending agent, an adsorbent anda binder. Disclosed slurries typically comprise an adsorbent and one ormore colloidal materials generally capable of forming a gel, such ascolloidal silica-based binders, colloidal alumina, colloidal zirconia,and mixtures of colloidal materials. The adsorbent can be formed insitu. Slurries can be water based, organic based or aqueous mixturescomprising organic materials.

[0013] Laminates are made by applying the slurry to support material oradmixing support material with the slurry. For support material havingtwo major planar surfaces, such as sheets, adsorbent compositions may beapplied to one or both sides of the support material. The slurry can beapplied to support material using a variety of techniques, includingusing a transfer roll, a roll coater, a split roll coater, a spraycoater, a sequester roller, a flooded-nip coater, etc. Adsorbentmaterial compositions also can be applied to support material by dipcoating, by electrophoretic deposition, and other methods known forcoating materials, such as are known for paper coating and otherindustries. Electrophoretic deposition can be used to apply adsorbentmaterial compositions to nonconducting supports by rendering suchsupports conducting by, for example, application of conductingmaterials, such as graphite.

[0014] For slurries applied to support material, the method may comprisemilling the slurry to form a milled slurry, and thereafter applying themilled slurry to the support material. Disclosed embodiments milled theslurry from an initial viscosity prior to milling of greater than 200cps, to a second viscosity subsequent to milling of less than 150 cps.Milling the intermediate slurry increases the density of the adsorbentmaterial applied to the support. For a lithium-exchanged zeolite,current embodiments used a zeolite having an initial particle size offrom about 3 to about 3.3 micrometers, and such zeolite was milled to asecond particle size of from about 2.5 to about 2.8 micrometers.

[0015] A particular disclosed slurry for applying to support materialcomprised water, isopropyl alcohol, Ludox (colloidal silica binder),naturally occurring zeolite products, such as Odorlok, and other desiredzeolites. Support material was selected from the group consisting ofconducting and nonconducting materials, including without limitation,glass fibers, ceramic fibers, scrim, stainless steel, metal foil, metalmesh, carbon fiber, cellulosic materials, polymeric materials, andcombinations of these materials. For metal-mesh support material, theslurry is advantageously applied to the metal mesh by electrophoreticdeposition. The metal mesh may be surface prepared prior to depositionof the slurry material, such as by oxidation, anodization, texturing,and combinations thereof.

[0016] Laminates also can be made by mixing support material with theadsorbent slurry compositions. In such cases, disclosed slurriestypically comprised colloidal materials generally capable of forminggels, such as colloidal silica, ceramic fiber, glass fiber and zeolite.One method for making such laminates includes depositing the slurry ontoa foraminous wire, draining the slurry material, and pressing thematerial to form a ceramic adsorbent paper. A reactive binder, such asan alginate-binder, can be applied to the slurry material on theforaminous wire.

[0017] After application to the adsorbent layers the adsorbent typicallyis macroporous, with a fine structure of micropores in the adsorbentmaterial within which the adsorptive separation takes place, with acoarser structure of macropores providing enhanced diffusive andconvective access from the flow channel to the micropores. The thicknessof the adsorbent layers on one or both sides of the channels must besufficient for effective function of the PSA process.

[0018] The dimensions of adsorbent structures may vary. However, typicaldisclosed adsorbent laminates have flow channel lengths of from about 1centimeter to about 1 meter, and more typically about 5 cm to about 30cm, a channel gap height of 50 to 250 microns, and an adsorbent coatingthickness of 50 to 300 microns on one or both sides of the sheets.Adsorbent laminates with these dimensions have been used in devicesoperating at PSA cycle frequencies up to at least 150 cycles/minute. Theflow channel length may be correlated with cycle speed. At low cyclespeeds, such as from about 20 to about 40 cycles per minute, the flowchannel length can be as long as one meter. For cycle speeds greaterthan 40 cycles per minute, the flow channel length typically isdecreased, and may vary from about 5 centimeters to about 30 cm. Thepresent invention contemplates that the adsorbent coating may be 5 to100 microns thick, more preferably about 25 to 60 microns thick, withthinner coatings used for cycle frequencies of 300 cycles/minute ormore.

[0019] Spacers can be formed on adsorbent laminates to space onelaminate from another. The spacer dimensions can be uniform, or can varyalong a laminate, such as increasing in height from a first end to asecond end of the laminate. Gas ventilation apertures also can be formedon laminates, which allow both fluid flow and diffusion to occur betweenadjacent channels, thereby facilitating pressure equalization in theadsorbent structure. Ventilation apertures typically are useful forcompensating for non-uniformity in flow channel structures anddimensions.

[0020] Adsorber elements comprising at least two laminates and includingspacers and perhaps ventilation apertures also are described. Adsorberelements can be stacked or otherwise configured in series along a gasflow path. Laminates and/or one or more adsorber elements describedherein are used in PSA processes and devices particularity rotary PSAdevices operating at high cycle frequencies. Such PSA devices can becoupled to other devices, such as fuel cells.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 illustrates a first laminate with an adsorbent coated onboth sides (double-sided coating) and a second laminate with adsorbentmaterial applied to just one side (single-sided coating).

[0022]FIG. 2 illustrates a roll coater for applying slurry compositionsto support material.

[0023]FIG. 3 illustrates a split roll coater for applying slurrycompositions to support material.

[0024]FIG. 4 illustrates one embodiment of a head box for applyingslurry compositions to support material.

[0025]FIG. 5 is an exploded view of the head box illustrated in FIG. 4.

[0026]FIG. 6A is a side schematic view of plural laminate sheetspositioned adjacent one another and spaced one from another by spacers.

[0027]FIG. 6B illustrates an adsorber element formed from the plurallaminates of FIG. 6A.

[0028]FIG. 7 illustrates a spacer formed by etching a metal foil with aphotolithograhic mask positioned on both sides of the foil.

[0029]FIG. 8 illustrates a spacer.

[0030]FIG. 9 illustrates a portion of an adsorbent laminate in the planeof flow channels.

[0031]FIG. 10 is a cross section of the laminate illustrated in FIG. 9taken along line A-A.

[0032]FIG. 11 is a cross section of the laminate illustrated in FIG. 9taken along line B-B.

[0033]FIG. 12 is a cross section of the laminate illustrated in FIG. 9taken along line C-C.

[0034]FIG. 13A is a schematic plan view of plural laminate sheetspositioned adjacent one another about a mold and having plural spacersfor spacing the laminate sheets one from another.

[0035]FIG. 13B illustrates an adsorber element formed from the plurallaminates illustrated in FIG. 13A.

[0036]FIG. 14A is a schematic plan view of a concentrically wound,continuous adsorbent sheet having spacers placed thereon to spaceconcentric rings of adsorbent sheets one from another.

[0037]FIG. 14B illustrates sectioning an adsorber element formed bybonding a spirally wound continuous laminate sheet.

[0038]FIG. 14C is a cross-sectional view of a containment chamber forhousing spirally wound laminates.

[0039]FIG. 14D is a plan view of a spider used in combination with thecontainment chamber illustrated in FIG. 14C.

[0040]FIG. 15A is a schematic side view of plural laminate sheets havingspacers therebetween of decreasing height in the direction of gas flow.

[0041]FIG. 15B illustrates a radial adsorber element formed by bondingtogether the plural laminate sheets of FIG. 15A.

[0042]FIG. 16 is a cross sectional side view of a section of anadsorbent structure according to the invention showing ventilationapertures defined in the adsorbent sheets.

[0043]FIG. 17 is a top view of one adsorbent sheet illustrated by FIG.16 having ventilation apertures formed therethrough.

[0044]FIG. 18 is a top plan view of an embodiment of a template used tomake laminates having ventilation apertures according to the invention.

[0045]FIG. 19 is a schematic view of a rotary pressure swing adsorptionapparatus particularly suitable for small-scale oxygen generation.

[0046]FIG. 20 is a cross section of the apparatus illustrated in FIG. 26taken along line 612-613.

[0047]FIG. 21 illustrates the porting of a rotor in planes defined bylines 614-615 and 616-617.

[0048]FIG. 22 illustrates a stator valve face in the plane defined bylines 614-615 with an exhaust compartment exhausting directly to a heavyproduct delivery conduit.

[0049]FIG. 23 illustrates a stator valve face in the plane defined bylines 614-615 with an exhauster comprising a vacuum pump and releasing acountercurrent blowdown stream at ambient pressure directly to a heavyproduct delivery conduit.

[0050]FIG. 24 illustrates a stator valve face along lines 616-617 ofFIG. 26 and a split stream light reflux expander for light refluxpressure letdown with energy recovery.

[0051]FIG. 25 illustrates a stator valve face along lines 616-617 andthe use of a throttle orifice for pressure letdown.

[0052]FIG. 26 is a schematic view of two adsorbent sheets havingapertures therethrough and with the adsorbent sheets staggered relativeto each other to define gas flow channels through the structure.

[0053]FIG. 27 is a schematic cross section of a stationary bed rotaryPSA.

[0054]FIG. 28 is a schematic cross section of a stationary bed rotaryPSA.

DETAILED DESCRIPTION I. Introduction

[0055] Gas separation devices that operate by preferential gasadsorption require an adsorbent structure over, through or about which agaseous mixture can be flowed to achieve gas adsorption. A slurrycomprising an adsorbent material or materials can be used to form theseadsorbent structures, referred to herein as laminates or adsorberelements. The slurry is combined with support material, or is applied tosupport material, to form adsorbent laminates or elements. Slurrymaterials, methods for making slurries comprising such materials, andmethods for making laminates or adsorber elements using the slurries,are described in more detail below.

II. Definitions

[0056] 1. Support—a support is any material to which or about whichadsorbent material is applied to form an adsorbent structure.

[0057] 2. Laminate—is a structure formed from a support and at least oneadsorbent material, and perhaps other materials, such as catalysts,over, about or through which a mixture of gasses can be flowed for gasadsorption, separation and/or a gas phase chemical reaction.

[0058] 3. Adsorber element—is a structure formed from plural laminates,or from an elongate laminate, such as a spirally wound laminate.

[0059] 4. PSA Apparatus—an apparatus that contains a process fluid andat least one adsorber material and enables a PSA process to occur withthe process fluid and the at least one adsorber.

[0060] 5. Spacer—A spacer is a structure or material that defines aseparation between adsorbent laminates. The type of spacers that can beemployed may consist of, but are not limited to, dimensionally accurate:plastic, metal, glass, or carbon mesh; plastic film or metal foil;plastic, metal, glass, ceramic, or carbon fibers and threads; ceramicpillars; plastic, glass, ceramic, or metal spheres, ovoids, or disks; orcombinations thereof.

III. Slurry Composition

[0061] The disclosed slurries generally include a liquid for suspendingsolids material, a binder, and an adsorbent and/or catalytic material,such as a zeolite.

1. Liquid

[0062] Water, polar organic liquids, and mixtures thereof are useful forsuspending slurry solids. Water is a primary liquid useful for formingsuitable slurries. Although not necessary, organic materials help theformulation and coating process, and may interact with the bindermaterial to facilitate the binding activity of the binder, and hence theformation of a stronger matrix for retaining the adsorbent material.

[0063] While a number of different organic materials optionally may beused, alcohols have been used in the disclosed embodiments. Particularlyuseful are aliphatic alcohols having 10 or fewer carbon atoms, referredto herein as lower alcohols. Most typically, the aliphatic alcohols arelower alkyl alcohols. Disclosed embodiments generally used isopropylalcohol.

2. Binder

[0064] The selection of the binder may depend on the particularadsorbent material selected, which in turn depends upon the task thatdevices comprising adsorbent laminates perform. Colloidal materialscapable of functioning as a binder and/or which form a gel areadvantageously used. Such colloidal materials include, withoutlimitation, colloidal silica-based binders, colloidal alumina, colloidalzirconia, and mixtures of colloidal materials. “Colloidal silica” refersto a stable dispersion of discrete, amorphous silicon dioxide particleshaving a particle size ranging from about 1 to about 100 nanometers.Disclosed embodiments used colloidal silicas having an average particlesize of from about 5 to about 40 nanometers, and an average surface areaof greater than about 200 m²/gram, typically in the range of from about220-230 m²/gram. Suitable colloidal silica materials also can be surfacemodified, such as by surface modification with alumina. Colloidalsilicas are commercially available from a number of companies, such asEka Chemicals, Grace Davison, Nalco, etc.

[0065] Ludox is one example of a colloidal silica binder used indisclosed embodiments. Ludox can be obtained in a number offormulations, including HS30 and HS40. Ludox can be used alone, or incombination with other materials, such as Odorlok. According to theZeolite-Material Safety Data Sheet (Canada), Odorlok comprises about 14%alumina, 3% calcium oxide, 1 percent magnesium oxide, and about 4%crystalline silica, the remainder being inert ingredients. Odorlokapparently bridges between zeolite particles, adding to the strength ofthe laminate produced relative to those formulations using solelycolloidal silica as the binder.

[0066] The strength of the laminate can be further enhanced by usingadditional strength increasing agents. Clay materials, such aspalygorskite (also known as attapulgite), which are hydrated magnesiumaluminum silicates, can be used as binders, alone or in combination withother binders. Palygorskite has an open crystal structure particularlyuseful for receiving the adsorbent.

[0067] Inorganic binders may be inert; however, certain inorganicbinders, such as clays, used with zeolite adsorbents may be convertedin-situ from kaolin binders to zeolite so that the zeolite is self-boundwith minimal inert material. Organic binder used to bind activatedcarbon particulates may be pyrolyzed to form a useful carbonaceousadsorbent.

3. Adsorbents and Catalysts

[0068] Virtually any adsorbent material can be used to practice thepresent invention. The selection of a particular adsorbent materialdepends primarily on the desired function, e.g. preferential adsorptionof one gas, such as nitrogen, versus other gases in a mixture, andsecondarily on other factors, such as availability and cost. Suitableadsorbent materials often are zeolites, which are highly crystalline,alumino-silicate materials comprising [SiO₄]⁴⁻ and [AlO₄]⁵⁻ tetrahedralunits. Zeolites typically have Si and Al joined by an oxygen bridge, andan overall negative charge, which requires positively charged counterions, such as Na⁺, K⁺ and Ca²⁺. The zeolite may be a hydrophilic zeolite(e.g., suitably ion-exchanged X, A or chabazite-type zeolites as usedfor air separation and hydrogen purification) or hydrophobic zeolite(e.g., Y, siliceous zeolite, silicate, or silicalite as used forseparating organic vapors from humid air).

[0069] Zeolites useful for adsorption separation of gases from mixturesare known, and are described in the patent and other literature.Examples include:

[0070] U.S. Pat. No. 2,882,244 discloses the direct synthesis and ionexchange of zinc X-zeolite from sodium X-zeolite using zinc nitrate;

[0071] Lithium X-zeolite was reported in U.S. Pat. No. 3,140,933 asbeing useful for nitrogen-oxygen separations;

[0072] U.S. Pat. No. 4,481,018 describes various polyvalent cation(particularly alkaline earth elements magnesium, calcium, strontium andbarium) X-zeolites and faujasites, which are known to have lowsilicon-to-aluminum ratios in the order of approximately 1 to 1.2;

[0073] U.S. Pat. No. 4,557,736 discusses modifying X-zeolites by ionexchange of available ion sites with several divalent cations to producea binary, ion-exchanged X-zeolite. The binary ions exchanged comprisecalcium and strontium having higher nitrogen adsorption capacity, lowheat of nitrogen adsorption and good nitrogen selectivity for airseparation;

[0074] X-zeolites can be exchanged with lithium to provide an improvednitrogen-selective adsorbent as set forth in U.S. Pat. No. 4,859,217,which states that an improved nitrogen adsorbent can be achieved when anX-zeolite is exchanged with lithium cations at greater than 88%exchange. The base sodium or sodium-potassium form of the X zeolite wasexchanged, utilizing conventional ion-exchange procedures and 4 to 12fold stoichiometric excesses of lithium salts;

[0075] Multiple cation exchange of zeolites with alkaline earth metalsis disclosed in U.S. Pat. Nos. 4,964,889;

[0076] U.S. Pat. No. 4,880,443, entitled “Molecular Sieve OxygenConcentrator with Secondary Oxygen Purifier,” teaches using a zeolitemolecular sieve bed having 5 AMG zeolite coupled to a carbon molecularsieve bed.

[0077] U.S. Pat. No. 4,925,460 describes lithium-containing zeolitechabazite.

[0078] U.S. Pat. No. 5,258,058, entitled “Nitrogen Adsorption with aDivalent Cation Exchanged Lithium X-Zeolite,” describes making sodium,potassium LSX-zeolite by the method of Kuhl (“Crystallization ofLow-Silica Faujasite” Zeolites 7:451 (1987). Lithium LSX-Zeolite wasprepared by ion exchange of sodium, potassium LSX-zeolite powder usingfive static exchanges at 100° C. with a 6.3-fold equivalent excess of2.2M LiCl. Sodium LSX-zeolite was prepared by ion exchange of sodium,potassium LSX-zeolite using three static exchanges at 100° C. with a4.2-fold equivalent excess of 1.1M NaCl. Various exchange levels of M²+,lithium LSX-zeolite were prepared by adding separate samples of theinitially prepared lithium LSX-zeolite powder to stoichiometric amountsof 0.1N M²+ salt solution with a pH between 5.6 and 7.0 and stirring atroom temperature for about 4 hours.

[0079] U.S. Pat. Nos. 5,174,979, 5,258,058, 5,413,625, 5,417,957,5,419,891 and 5,152,813, and 5,464,467 describe binary lithium- andalkaline-earth-exchanged X zeolites;

[0080] EPA 0685429 and EPA 0685430 describe lithium-containing zeoliteEMT; and

[0081] U.K. Patent No. 1,580,928 describes a process for making lowsilica X-zeolites (“LSX”; where LSX is X-zeolite with a Si/Al=1 in thereference). The process comprises preparing an aqueous mixture ofsources of sodium, potassium, aluminate and silicate and crystallizingthe mixture at below 50° C., or aging the mixture at 50° C. or below,followed by crystallizing the same at a temperature in the range of 60°C. to 100° C.;

[0082] The properties and uses of alkali metal exchanged zeolites arereviewed by D. Barthomeuf in “Basic Zeolites: Characterization and Usesin Adsorption and Catalysis,” published in Catalysis Reviews, Scienceand Engineering, (1996), Vol. 38, N4, p.521. Cation exchange of zeolitesalso occurs when the base zeolite is brought into intimate, solid-statecontact with salts of the desired cations, and, if necessary, heatingthe mixture. This is discussed in detail by Karge [H. G. Karge: “SolidState Reactions of Zeolites”, in Studies in Surface Science andCatalysis, Vol. 105C, Elsevier (Amsterdam) (1996), “Progress in Zeoliteand Microporous Materials” (H. Chon, S.-K. Ihm and Y. S. Uh (Editors)p1901-1948). Solid-state ion-exchange between zeolite sodium Y and metalchlorides (including lithium and potassium chlorides) is described byBorbely et al. (G. Borbely, H. K. Beyer, L. Radics, P. Sandor, and H. G.Karge: Zeolites (1989) 9, 428-431];

[0083] Gunter and H. Kuhl in “Crystallization of Low-Silica Faujasite”Zeolites (1987) 7, p451 disclose a process for making low silicaX-zeolites comprising dissolving sodium aluminate in water with theaddition of NaOH and KOH. Sodium silicate was diluted with the remainingwater and rapidly added to the NaAlO₂—NaOH—KOH solution. The gelledmixture was then aged; and

[0084] Ion-exchanging zeolites is discussed at length in chapter 8 ofthe comprehensive treatise of Breck (Donald W. Breck: “Zeolite MolecularSieves”, Pub. Wiley, N.Y., 1973). Conventional ion exchange of zeolitesis carried out by contacting the zeolite, in either powdered oragglomerated form, using batch-wise or continuous processes, withaqueous solutions of salts of the cations to be introduced. Theseprocedures are described in detail in Chapter 7 of Breck, and have beenreviewed more recently by Townsend [R. P. Townsend: “Ion Exchange inZeolites”, in Studies in Surface Science and Catalysis, Elsevier(Amsterdam) (1991)].

[0085] The adsorbent may be selective at an elevated operatingtemperature (e.g., about 250° C. to about 800° C.) for carbon dioxide.Suitable such adsorbents known in the art include alkali-promotedmaterials. Illustrative alkali-promoted materials include thosecontaining cations of alkali metals such as Li, Na, K, Cs, Rb, and/oralkaline earth metals such as Ca, St, and Ba. The materials typicallymay be provided as the hydroxide, carbonate, bicarbonate, acetate,phosphate, nitrate or organic acid salt compound of the alkali oralkaline earth metals. Such compounds may be deposited on any suitablesubstrate such as alumina. Examples of specific materials includealumina impregnated with potassium carbonate and hydrotalcite promotedwith potassium carbonate.

[0086] Mixed ion adsorbents also can be used. Examples, withoutlimitation, of suitable mixed ion adsorbents include lithium-basedzeolites containing silver and copper, such as those described in Yanget al.'s international application No. PCT/US99/29666, internationalpublication number WO 00/40332, which is incorporated herein byreference.

[0087] Dessicants

[0088] U.S. Pat. No. 4,711,645 Kumar (AP), “Removal of water and CO₂from atmospheric air” discusses the use of activated alumina, zeolite(13X, 5A, Na mordenite) for pressure swing adsorption processes.

[0089] Ghosh, T K “Solid Dessicant Dehumidification System”, Stud. Surf.Sci. Catal., Vol. 120 (1988), p.879, discusses temperature swingprocesses, and particularly SiO₂, activated alumina, 13X, andhydrophobic zeolite for H₂O removal.

[0090] VOC

[0091] U.S. Pat. No. 5,968,235, Grime (Ransburg Corp.) “Method for VOCAbatement,” discusses alumino-silicate gels for removing VOCs.

[0092] Air Pre-purification

[0093] Rege, S U, “Sorbents for Air Purification in Air Separation,”Chem. Eng. Sci., 55 (2000) pp. 4827-4838 13X, AA, clinoptilolite (K, Ca)for pressure and temperature swing adsorption processes.

[0094] U.S. Pat. No. 5,052,188 Komarneni (Gas Res. Inst.), “Dessicantmaterial for use in gas fired cooling and dehumidifying Equipment,”discusses Y-type zeolite for H₂O removal.

[0095] U.S. Pat. No. 667,560, Dunne (UOP), entitled “Ce-exchangedzeolite Y for water removal.”

[0096] U.S. Pat. No. 4,702,749, Sircar (AP), “Techniques for surfaceoxidation of activated carbons” which discusses using 13X and activatedalumina for presssure and temperature swing adsorption.

[0097] U.S. Pat. No. 5,232,474, Jain (BOC) “Pre-purification of air,”discusses use of activated alumina for CO₂, H₂0 separation from air.

[0098] U.S. Pat. No. 5,587,003, Bulow, Clinoptilolite, discusses CO₂removal from air for pressure swing adsorption processes.

[0099] Hydrogen Separation and Purification

[0100] U.S. Pat. No. 5,897,686, Golden (AP), “CO₂ removal from H₂, CO₂and CO” for pressure swing adsorption using 13X (1^(st)), 3A (2^(nd)).

[0101] CO and Olefin Separation

[0102] U.S. Pat. No. 4,717,398 Pearce (BP Chemicals) discusses CuY,Si/Al 1.5-3.0 zeolites.

[0103] U.S. Pat. No. 3,789,106 Hay (l'Air Liquide) discusses CuMordenite

[0104] U.S. Pat. No. 5,175,137, Golden (Air Products) discusses Cu onactivated alumina, carbon

[0105] U.S. Pat. No. 4,917,711, Xie (Peking Univ.), discusses CuCl onzeolite, alumina, silica, activated carbon

[0106] U.S. Pat. No. 3,497,462, Kruerke (Union Carbide) discussessynthesis of Cu(I) zeolites

[0107] CO₂ Removal

[0108] U.S. Pat. No. 5,980,611, Kumar (BOC), discusses Si/Al>1.5 zeolitefor CO₂ removal”

[0109] U.S. Pat. No.5,531,808, Ojo (BOC) “CO₂ removal from gas streamsusing LSX zeolite” discusses many different cations.

[0110] CO Removal

[0111] U.S. Pat. No. 4,765,808 Oigo discusses BaX for CO removal over N₂

[0112] CO₂ Purification

[0113] Chue, K. T. Ind. Eng. Chem. Res., 1995, 34, 591-598 discussesactivated carbon vs 13X for CO₂ recovery

[0114] CO Removal in PSA by Sn Activated Carbons

[0115] Iyuke, S. E., Chem. Eng. Sci. 55 (2000) 4745-4755

[0116] Chabazite

[0117] U.S. Pat. No. 4,925,460, Coe (AP), discusses lithium chabazites.

[0118] U.S. Pat. No. 4,747,854, Maroulis discusses cation exchangedmaterials, including Ca, Mg, Ni, Na and compares Ca X, Ca, Mordenite andCa, chabazite.

[0119] U.S. Pat. No. 4,732,584, Coe, disucsses Ca chabazite andpurification rather than bulk separation.

[0120] Water Gas Shift

[0121] It is known [J. J. Verdonck, P. A. Jacobs, J. B. Uytterhoeven,“Catalysis by a Ruthenium Complex Heterogenized in Faujasite-typeZeolites: the Water Gas-Shift Reaction”, J. C. S. Chem Comm., pp.181-182, 1979] that ruthenium complexes stabilized within X or Yzeolites provide greater water-gas shift catalytic activity thanconventional copper based catalysts. Other water gas shift catalystsknown in the art include platinum supported on ceria and transitionmetal carbides. Iron-chrome catalysts are used for industrial water gasshift reactions at higher temperatures. Keefer et al.'s U.S. Patentapplication entitled “Systems and Processes for Providing Hydrogen toFuel Cells,” filed Oct. 26, 2001, incorporated herein by reference.

[0122] Hydrogen Purification

[0123] Sircar, S. and Golden, T. C.—“Purification of Hydrogen byPressure Swing Adsorption,” Separation Sci and Technol, 35(5), pp.667-687, 2000, which discusses 5A and activated carbon.

[0124] Sircar, S. and Golden T. C., “Sep. Sci. Tech., Vol. 35, issue No.5, p. 667 (2000), which references standard adsorbents for pressureswing adsorption processes.

[0125] Adsorbents and catalyst can be used in Separation EnhancedReactors (SER). Examples of SER systems include the steam methanereforming and ammonia synthesis. Steam methane reforming is used toproduce hydrogen from natural gas. A steam reforming catalyst (e.g.nickel or a platinum group metal supported on alumina) and a hightemperature carbon dioxide adsorbent are supported in thereactor/adsorber. The carbon dioxide adsorbent may be based onpotasssium carbonate promoted hydrotalcite as developed by J. R. Hufton,S. G. Mayorga and S. Sircar “Sorption Enhanced Reaction Process forHydrogen Production, AIChEJ 45, 248 (1999)), or another high temperaturecarbon dioxide adsorbent likewise effective in the presence of highsteam partial pressure.

[0126] In the example of ammonia synthesis, the reactants are hydrogenand nitrogen, which react to produce ammonia. A bench scale apparatuswas operated with a single granular adsorber in the mechanicalembodiment of U.S. Pat. No. 4,702,903. The adsorber was loaded withreduced iron catalyst 301, 13-X zeolite and silica gel as theadsorbents.

[0127] Ethanol dehydration can be accomplished by using 3A(potassium Azeolite).

[0128] Zeolites also are commercially available from such sources asZeolyst, of Valley Forge, Pa.

[0129] Materials other than zeolites can be used alone or in combinationto form laminates and adsorber elements comprising slurry material. Forexample, the adsorbent may be an alumina gel or an active carbon,including carbon fibers. The adsorbent may be catalytically active, ormay include an admixture of a catalyst. The adsorbent material also maybe a precursor (e.g., metakaolin) that is converted to a usefuladsorbent in situ after formation of the laminate, such as after beingcoated onto a support.

[0130] The adsorbent material typically is used as finely dividedparticles, preferably with a narrow, substantially uniform sizedistribution. The particles generally are less than 10 microns in size,more typically less than 5 microns. Particle size preferably is selectedto provide suitable macroporous diffusion.

4. Additional Materials

[0131] Materials in addition to those described above can be added tothe disclosed slurries. One example of such material is a water-soluble,high molecular weight, polymeric organic material, such ashigh-molecular-weight polyvinyl alcohol. High-molecular-weight materialstypically are used when support material is added to the slurry, asopposed to support materials where the slurry is applied to the support.These high-molecular-weight materials are added to the slurries toimprove laminate green strength (i.e., strength prior to firing).

[0132] Flocculating agents also can be used to form the disclosedslurries. Flocculating agents generally are used when the supportmaterial is added to the slurry. One example of a useful flocculatingagent is cationic starch when used in combination with binder material,such as colloidal silica.

[0133] For electrophoretic deposition (EPD), long chain polymeric fibersof, for example, about 0.1 micron to about 5 microns in diameter andabout 1 micron to about 150 microns in length may be charged positivelyat one end or negatively at the other end, and added to the suspensionto orient in the field direction normal to the laminate sheet beingcoated. These fibers entering the coating preferentially orient more orless perpendicular to the substrate. The fibers may be located randomlyin the coating, but also may be guided by electrostatic field gradientsestablished by a template to locate the fibers approximately in aregular (e.g. hexagonal) pattern. Upon subsequent firing of theadsorbent coating, these fibers will be removed by volatilization,pyrolysis or combustion to define opened, straight macropores asdesired. If the fibers are located in a regular array within the coatingby a template, they define a columnar array of macropores, desirablywith approximately equal spacing.

IV. Relative Material Amounts in Disclosed Slurries 1. Slurries forCoating Supports

[0134] For slurries that are applied to support material, one goal ofthe present invention is to increase the amount (i.e., density asdetermined by mass of zeolite per unit area of support) of adsorbentmaterial applied to a support. This requires increasing the amount ofzeolite that can be added to the slurry. The disclosed invention hassignificantly increased the amount of adsorbent material that can beapplied to a support relative to known compositions.

[0135] The typical solids-to-liquid fraction in disclosed embodiments ofsuch slurries is about 40% liquid/60% solids by weight. One example of a2-liter slurry composition that has been applied to supports to formcertain embodiments of the disclosed laminates is provided below inTable 1. TABLE Approximate Material Amount Weight Percent 1. Water 1.525 grams 1. 21 2. Isopropyl Alcohol 2. 140 grams 2. 6 3. Ludox HS40 3.250 grams 3. 10 4. Odorlok 4. 110 grams 4. 4 5. Zeolite 5. 1500 grams 5.59 (comprising about 25% water by weight of zeolite)

2. Slurries Comprising Support Material

[0136] Slurries comprising support material generally are lessconcentrated with respect to the amount of adsorbent material added tothe slurry relative to slurries applied to support material. Forexample, disclosed embodiments with support material added theretotypically comprise less than about 20% by weight solids, generally 10%or less solids, and typically from about 2% to about 10% by weightsolids.

[0137] Table 2 provides relative amounts of dry materials added to formone example of a slurry having support material admixed therewith. Theceramic fiber has an average diameter of less than about 10 microns, andtypically from about 3 microns to about 6 microns. The glass fibers arerelatively long fibers having average typical lengths longer than about12 millimeters, and preferably shorter than about 50 millimeters. Themilled glass fibers have fiber diameters of less than about 20 microns,with diameters generally ranging from about 10 to about 15 microns.TABLE 2 Material Weight Percent 1. Colloidal silica 1. 2%-25% 2. CeramicFiber 2. 0%-25% 3. Glass Fiber 3. 2%-20% 4. Zeolite 4. 50%-90%

V. Slurry Formation

[0138] Slurries of the disclosed invention were prepared in a high shearmixer. The order in which materials are mixed can be varied, and themixing order is not critical to the effectiveness of the slurry formed.

[0139] All nonabsorbent materials were added to form a homogenousmixture. Adsorbent material is then added to the homogeneous mixtureslowly with continued mixing. As the adsorbent material is added, theviscosity of the mixture increases. The viscosity of the slurry soformed, referred to herein as an intermediate slurry, is about 230centipoise (cps) at 25° C. and a mixer speed of about 100 rpm asmeasured by a Brookfield viscometer.

[0140] A ball or jar mill is used to change the particle sizedistribution of the intermediate slurry. Portions of the slurry areplaced in containers containing milling agents, such as ceramic rocks,and the jars are placed on a jar mill. The processing time of theintermediate slurry by the jar mill varies depending on a number offactors, including amount of slurry in the jar, size of the millingstones, initial viscosity of the slurry, jar rotation rate, etc. Workingembodiments of the process have wet milled the slurry components for aperiod of time of from about 10 minutes to about 3 days, with a typicalmilling time being from about 4 to about 24 hours. Milling theintermediate slurry decreases the slurry viscosity from a firstviscosity at 25° C. of greater than about 200 cps, typically about 230cps, to a second viscosity typically less than about 150 cps, such asabout 140 cps.

[0141] Milling the slurry provides several significant advantages forslurries applied to support material. Changing the average particle sizedistribution of the intermediate slurry increases the density of theadsorbent on the laminate. Moreover, changing the average particle sizedistribution of the intermediate slurry produces a better laminate withgreater strength and less dusting propensity.

VI. Adsorbent Support Materials

[0142] Any material to which the disclosed slurries can be applied toform a laminate, or which can be added to the slurry to form a laminate,and then be useful in a gas separation or gas phase reaction device, canbe used as a support material. Such materials include, withoutlimitation, glass fibers, milled glass fiber, glass fiber cloth, fiberglass, fiber glass scrim, ceramic fibers, metallic woven wire mesh,expanded metal, embossed metal, surface-treated materials, includingwithout limitation surface-treated metals, metal foil, metal mesh,carbon-fiber, cellulosic materials, polymeric materials, andcombinations of these materials. Monolithic structures, extruded orotherwise, such as cordiorite, also can be used. Coated supportstypically have two major opposed surfaces, and one or both of thesesurfaces can be coated. See FIG. 1, which illustrates both a doublesided coating 2 and a single sided coating 4. The support 6 for bothillustrated embodiments is stainless steel wire mesh. Double-sidedcoatings 2 have an adsorbent layer thickness designated as X in FIG. 1A.Single-sided coatings have an adsorbent layer thickness designated as Yin FIG. 1B. Support sheets may be individual, presized sheets, or may bemade of a continuous sheet of material. The thickness of the substrateplus applied adsorbent or other materials (such as desiccant, catalyst,etc.) typically ranges from about 10 micrometers to about 500micrometers, more typically from about 150 micrometers to about 300micrometers.

[0143] Metallic mesh supports provide desirable thermal properties ofhigh heat capacity and conductivity which “isothermalize” the PSA cycleto reduce temperature variations that degrade the process when conductedunder more adiabatic conditions.

[0144] Metal foils are manufactured with highly accurate, thicknessdimensional control. Hence there is a need for a method to coat metalfoils with a thin adsorbent layer of accurately controlled thickness,with necessary good adhesion. One method for doing this iselectrophoretic deposition.

[0145] The metal foil may be composed of, without limitation, aluminum,steel, nickel, stainless steel or alloys thereof. For adhesion of theelectrophoretic adsorbent coating on the foil, the metal foil surfacemay be oxidized and preferably roughened for favorable wetting andbonding properties. An oxide coating may be applied by heating in afurnace with air or oxygen, as disclosed by Dunne (U.S. Pat. No.5,260,243) for slip-coating zeolite slurries onto aluminum tubes. Asdisclosed by Chapman et al. in U.S. Pat. Nos. 4,279,782 and 4,331,631,the foil may be formed by metal peeling of an aluminum-containing,ferritic stainless steel and processed so that alumina whiskers willsubstantially cover the oxide film.

[0146] A preferred approach for preparing the oxide surface of analuminum foil is by anodization under acidic conditions so as to form analumina layer approximately 1 to 2 microns thick, with a dense hexagonalcolumnar array of pores regularly spaced approximately 0.2 to 1.5microns apart. As discussed by Furneaux et al. (U.S. Pat. No.4,687,551), pore spacing is proportional to applied voltage, and wouldbe about 0.5 micron with an anodization voltage of 200 V. The anodicpore structure provides excellent adhesion, and can usefully act as atemplate for forming a desirable regular columnar orientation ofmacropores on the hexagonal pattern of the anodic film pores. During theelectrophoretic coating process, the hexagonal template pattern perturbsthe electrostatic field in the coating being formed to create apreferred distribution of porosity with the desired columnar array.

[0147] Other methods of microtexturing the base surface can be used. Forexample, a photolithographic mask can establish a regular pattern tosimilarly distort the electrostatic field in the coating underdeposition. Any such technique likewise may be used to provide atemplate pattern for achieving deposition of the adsorbent coating withoriented macropores in that pattern and normal to the final laminatesurface, thereby approaching the ideal of a non-tortuous macroporenetwork as highly desirable for excellent mass transfer under highfrequency operating conditions.

[0148] The laminate sheet may be formed upon a metal substrate whosewidth is equal to the length of the laminate adsorber in the flowdirection within the PSA process. The substrate width also could be anintegral multiple of the adsorber length, before subsequently formingthe substrate to size. It is desirable that the sheet coating be appliedin the direction orthogonal to the future flow direction afterinstallation, so that any transverse coating irregularities will bedistributed equally in the flow channels. After a roll of the metal foilhas been coated, such as by passing continuously through an EPD bath, itmay be dried and fired (if required) at a temperature of from about 150°C. to about 800° C. The roll may be cut into sheets of the appropriatesize to be assembled in the laminate adsorber.

[0149] Alternatively, the laminate adsorber may be assembled from aplurality of strips to be installed orthogonal to the flow direction,and whose width is a fraction of the installed flow direction length ofthe laminate adsorber. Each sheet layer then consists of a plurality ofseparate strips. Flow channels through the adsorber will thus traverse aplurality of these strips in passing from the feed end to the productend of the adsorber. The strips may be advantageously prepared ofdifferent adsorbent materials and/or catalyst materials when theprocess, such as a PSA process, requires a layered adsorber withdifferent adsorbents and/or catalysts in different zones along thelength of the flow channels. For example, the adsorbent in the firststrip at the feed end may be alumina or other desiccant. Adsorbentstrips toward the product end may use more selective adsorbents whosefunction may be impaired by excessive humidity. The strips may be basedon metal foil ribbons individually coated by EPD in separate baths foreach adsorbent material.

VII. Methods for Forming Laminates

[0150] Generally, process rates exhibit mass transfer resistances due inpart to various surface resistances. Laminates are used to minimizethese resistances by (a) providing a high-surface-to-volume ratio, and(b) making a uniform minimum thickness structure supporting the activeadsorbent/catalyst.

1. Coating Support Material

[0151] A. Roll Coating

[0152]FIG. 2 shows a roll coater that can be used to apply disclosedslurry compositions to one or both sides of support material. Withreference to FIG. 2, a coating system 10 comprises a container 12 forreceiving adsorbent slurry. A roller 14 supported by, and rotatingabout, an axle 16 powered by a motor (not shown), is positioned so thata portion of the roller is within the slurry 18. A travelling web ofsupport material 20 is moved across a surface 22 of the roller 14 wettedby immersion in the slurry 18. In this manner, one side of the travelingweb of support material 20 is coated with the adsorbent slurry 18. Ifthe support material 20 is porous, such as with metal mesh, fiberglass,or combinations thereof, then coating one side of the supporteffectively applies slurry material to both sides of the support.However, not all support materials are porous. If only one side of anon-porous support material is coated, then the uncoated side can act asa spacer for spacing coated sides one from another. Alternatively, asecond side of the travelling web 20 can be coated with the same slurrymaterial 18, or a different slurry material, by a passing the oppositeside of the support material over the roller 14.

[0153]FIG. 3 illustrates a split roll coater system 30 that can be usedto apply different coating compositions to different sections of asupport material. The illustrated embodiment of a split roll coatersystem 30 comprises a container 32 having a first section 34 forreceiving a first adsorbent composition 36. Container 32 also includes asecond section 38 for receiving a second adsorbent composition 40, whichcan be the same as or different from the first slurry composition 36.Generally, the split roll coater system 30 is used to apply twodifferent slurry compositions to a support. If two different slurrycompositions are used, then sections 34 and 38 are separated one fromanother by a wall or baffle 42 to prevent the adsorbent compositions 36and 40 from mixing.

[0154] Positioned in section 34 is a first roller 44. Positioned insection 38 is a second roller 46. Rollers 44 and 46 can be supported,and rotated about, a common axle 48. Alternatively, the rollers 42 and44 can be supported by and rotate about separate axles. Support material50, such as in the form of a continuous sheet, is moved across a surface52 and 54 of rollers 44 and 46 respectively having adsorbentcompositions 36 and 40 applied thereto by rotation of the rollersthrough the compositions.

[0155] Adsorbent compositions can be pumped to a head box 60 forapplying slurry composition to support material. FIG. 4 illustrates oneembodiment of a head box 60, and FIG. 5 provides an exploded view ofthis head box. A travelling support material (not shown) is moved so asto contact the slurry composition, thereby coating at least one side ofthe support material with adsorbent composition. The illustrated headbox 60 comprised a motor 62 coupled to an axle 64. Axle 64 drives a rollcoater, such as the split roll coater 30 and container 32 discussedabove. A pump (not shown) delivers adsorbent slurry composition tocontainer 32. Container 32 includes overflow chambers 66 a, 66 b fordraining slurry material from container 32 through slot 68 and into aslurry reservoir (not shown). Metering blade 70 is used to keep theamount of slurry on the roll coater 30 fairly constant. The head box 60also includes a doctor blade 72 over which support materials passes.Doctor blade 72 is used to remove excess slurry material from thesupport material.

[0156] After the support is coated with adsorbent composition, it isthen dried to set, and potentially cure, the composition on the supportmaterial. Drying can be accomplished by any suitable method, such asconvection heating, induction heating, IR heating, microwave heating,and combinations of these methods.

[0157] B. Electrophoretic Deposition

[0158] Slurry compositions may be electrophoretically applied to therigid support material, such as by using the method described in BowieKeefer et al.'s prior Canadian patent application No. 2,306,311,entitled “Adsorbent Laminate Structure,” filed on Apr. 20, 2000, whichis incorporated herein by reference.

[0159] EPD is a technique for applying high quality coatings of uniformthickness to metal substrates. The method can be used to apply organicand inorganic particulate coatings on electrically conductivesubstrates. Examples of methods for electrophoretic deposition ofindustrial materials include Emiliani et al. (U.S. Pat. No. 5,415,748)for deposition of metallic oxide coatings; Friedman et al. (U.S. Pat.Nos. 5,591,691, 5,604,174 and 5,795,456) for deposition of aluminacatalyst support on stainless steel foils for automotive catalyticconverters; and Appleby (U.S. Pat. No. 4,555,453) for deposition ofmolten carbonate fuel cell electrolyte and binder.

[0160] Generally, EPD involves forming a slurry in an aqueous ornon-aqueous suspension, together with any appropriate organic orinorganic binders, dispersants, surfactants, defoaming agents,polyelectrolytes, etc. EPD may be conducted with the metal foil as anelectrode contacting the suspension in a bath having a counterelectrode.The foil may be the cathode or anode, according to the charge of thesuspended adsorbent particles respectively either positive or negative.In an aqueous EPD process, an acidic pH typically would be used forcathodic deposition, and an alkaline pH for anodic deposition.

2. Admixing Support Material with Adsorbent and/or Catalyst Slurries

[0161] Laminates can be formed by admixing support materials withdisclosed slurry compositions. For example, a ceramic paper laminate canbe made by first forming a weak slurry, e.g., less than 10% by weightsolids, comprising: adsorbent and/or catalyst material (e.g., from about50%-90% by weight of the solids); ceramic fiber (generally up to about25% by weight of the solids); glass fiber (from about 2% to about 20% byweight of the solids); and colloidal silica binder (from about 2% toabout 25% by weight of the solids); and any desired organic binder (upto about 10% by weight of the solids). A flocculating agent, such ascationic starch, optionally can be added to the slurry in amountssufficient to flocculate the colloidal silica and fibers into flocswithin the slurry.

[0162] The flocculated slurry is then formed into laminates. One methodfor forming ceramic paper-like laminates is to deposit the flocculatedslurry onto a foraminous wire and then allow the composition to drain.Further drainage can be achieved using press rollers, and/or doctorblades as desired. The composition on the wire also can be drained undervacuum. The ceramic paper formed in this manner is then dried and may bepressed further using heated press rolls.

[0163] Additional setting agents can be applied to the material oncedeposited onto the foraminous wire. For example, reactive binders, suchas sodium alginate, can be added to the slurry, and/or applied to theslurry material, such as by spraying, after it is deposited onto thewire. Setting agents can be used to initiate the reaction required toactivate the binder. For example, if an alginate-based binder is used,then cationic solutions may be applied to the green paper (paper priorto the binder setting) subsequent to the application of the alginatebinder.

VIII. Flow Channels and Spacers

[0164] Gas flow channels are defined in adsorber elements to allow gasflow therethrough. Generally, gas flow channels should provide for lowfluid resistance coupled with relatively high surface area. Flow channellength should be sufficient to confine the mass transfer zone, which is,at least, a function of the fluid velocity, and the surface area tochannel volume ratio. The channels preferably are configured to minimizepressure drop in the channels. In many embodiments, a fluid flowfraction entering a channel at the first end of the adsorber elementdoes not communicate with any other fluid fraction entering anotherchannel at the first end until the fractions recombine after exiting thesecond end. In can be recognized that channel uniformity is important toensure that substantially all of the channels are being fully utilized,and that the mass transfer zone is substantially equally contained. Thefollowing methods for making spacer embodiments provide a method formaking spacers having a set of channels, and to make the channelssubstantially dimensionally uniform.

[0165] Gas flow channels can be established by placing adsorbent sheetshaving flow apertures therethrough adjacent one another, and thenstaggering the alignment of such sheets to define gas flow channels.This embodiment is illustrated by FIG. 26, which shows a structure 800having a first adsorbent sheet 802 and a second adsorbent sheet 804placed adjacent one another. Each adsorbent sheet 802, 804 definesapertures therethrough. The illustrated apertures are substantiallysquare, but this is not necessary for proper operation, and instead suchapertures could be any geometric shape, including without limitation,lines or slots, round apertures, rectangular apertures, etc.

[0166] The adsorbent sheets 802 and 804 are substantially identical.Adsorbent sheets 802 and 804 are positioned to define gas flow channelswithout the need for spacers between the adsorbent sheets. In theillustrated embodiment, sheet 802 is positioned first, and then sheet804 is flipped over and displaced relative to sheet 802. Thisarrangement defines gas flow channels through the structure.

[0167] Flow channels also may be established between by spacers thatform parallel channels between adjacent laminates. The channel widthbetween adjacent adsorbent sheets of the adsorbers has been in the rangeof from about 25% to about 200% of the adsorbent sheet thickness. Thisconfiguration has much lower pressure drop than packed pelletizedadsorbers, and avoids the fluidization problem of packed adsorbers.Adsorbent sheets are typically in the range of from about 50 to about400 micrometers thick, and are sufficiently compliant to accommodatestacking or rolling. Spacer systems provide the necessary stabilityagainst unrestrained deflections or distortions that degrade theuniformity of the flow channels between adjacent layers of adsorbentsheets.

[0168] Spacers are made of any elastically deformable material, such asceramics or metals, and may be applied to, introduced to, or otherwisemade integral with the laminate sheets using any suitable method. Forexample, if ceramic spacers are used, the spacers may be applied to thelaminate sheets by providing a certain thickness and area of a ceramicslurry to the laminate sheets and curing the slurry to form the spacers.In particular embodiments, the spacers are applied using a methodsimilar to screen or stencil printing. A stencil is placed over thelaminate sheet and the slurry is applied over the stencil, such as bypouring, brushing, screen printing (such as by using a doctor blade), orspraying. The stencil defines apertures for receiving the ceramic slurryand, when placed on the laminate sheet, these apertures form wells ontop of the laminate sheet. Slurry applied to the laminate sheet collectsin the wells. Thus, the spacers are positioned on a first surface of thelaminate sheet by the pattern of apertures within the stencil. This isillustrated in FIG. 6 with reference to plural laminate sheets 90. Whenthe slurry is cured, spacers 92 bond to a first surface 94 of thelaminate sheet 90 as illustrated in FIG. 6a.

[0169] The spacers may be any suitable size and shape, including withoutlimitation, round, teardrop shaped, double tear dropped, columnar, starshaped, spherical, etc. The thickness or height of the spacersdetermines the spacing between laminate sheets, and spacers typicallyrange in thickness from a few micrometers to several millimeters.Particular embodiments employ spacers having a thickness of about 10 to250 micrometers, such as about 50 to 150 micrometers. Spacers may rangein width or diameter from a few micrometers to a few centimeters. Insome embodiments, the widths or diameters of the spacers are in themillimeter range, such as about 1 to 10 millimeters or, generally about2 to 8 millimeters, and typically from about 3-5 millimeters. In anyparticular embodiment, all spacers may be the same size, or the spacersmay vary in size throughout the laminate sheet or adsorber element.

[0170] The spacers may be placed on a first surface of the laminatesheet in a random or ordered pattern. For example, the spacers may beplaced in an ordered grid with substantially identical distancesseparating each spacer from its neighbors. Alternatively, the spacersmay be placed in a series of concentric circles, a substantially linearpattern, or any other desired pattern.

[0171] If the spacers are formed on the laminate sheet using a ceramicor other slurry, the spacers are then set and/or cured, i.e., allowed todry to form a raised structure, which can be used to separate thelaminate sheets one from another. The spacers may be set and/or cured atroom temperature, though heat may be applied during curing of thespacers, such as by blowing warm or hot air over the spacers, or byusing IR, convection heating, inductive heating, etc. Additionally,pressure may be applied to the spacers to aid in curing, if desired.

[0172] The spacers may be modified to a particular profile, such as byshaving, roll pressing, nip rolling, calendering or abrading. If thespacers are shaved or abraded, a height guide may be used to control theshaving or abrading to provide a more uniform spacer height. Forexample, a second stencil of slightly lesser thickness than the stencildescribed above having a pattern of apertures conforming to the patternof spacers on the laminate sheet may be placed on top of the laminatesheet. The spacers are then shaved or abraded down to the surface of thesecond stencil.

[0173] Spacers may be formed by embossing a raised pattern of bosses orridges (parallel to the flow channels), so that coating over thosebosses or ridges establishes the spacers. The laminate assembly mustthen be configured to avoid nesting of male and female indentations, forexample by forming each sheet from two foils of which only one isembossed while the other remains flat. Alternatively, a raised patternof metallic layers may be formed by electroforming or etching of themetal foil. Alternatively, a spiral laminate may be made where thespacers do not nest.

[0174] Spacers alternatively may be provided in the process by maskingduring part of the deposition process so as to create a raised pattern.

[0175] In alternative preferred embodiments as described below, spacersare provided as a separate fabricated assembly to be installed betweenlaminates.

[0176]FIG. 7 shows a spacer 101 formed by etching a metal foil with aphotolithographic mask on both sides. Channels 102, 103 are created bythrough etching simultaneously from both sides to create open areas,while full thickness spacer ribs 104 between the channels are defined bythe mask on both sides. Lateral struts 105 are formed at intervals byetching the struts only from one side while masked on the other side.The edge 106 of the spacer is defined by masking from both sides, with asuitable width for installation, for example by bonding in the laminatestack of alternating sheets and spacers.

[0177]FIG. 8 shows a spacer 110 which may be fabricated in several ways.For example, spacer 110 may be made (1) from metal foil by etchingfollowed by rolling to reduce the thickness of the struts 105, (2) bydiffusion bonding of thin foil strips laid across each other, or (3) bya thermoplastic molding.

[0178] FIGS. 9-12 show an adsorbent laminate structure 300. Typicalsheets 301 and 302 comprise adsorbent strips, e.g. 304 and 305, madehaving coatings applied thereto, such as EPD coatings 306 and 307, onboth sides of substrate ribbons, e.g. 308. The ribbons have a width “w”in the flow direction indicated by arrow 310.

[0179]FIG. 10 illustrates a “woven-wire mesh spacer 320 used in eachflow channel 321, between adjacent pairs of sheets 301 and 302. Eachsheet in the depicted embodiment comprises multiple ribbons or strips304 and 305, although it will be understood that the disclosed spacer320 may be used as spacers with continuous rather than ribbon sheets.The spacer 320 comprises first and second wires. The first and secondwires can have the same diameter, or can be of substantially differentdiameters. Various configurations of wire diameter sizes have been made,and thereafter tested in PSA apparatuses. The illustrated embodimentsused wires having diameters, preferably with channel-defining wireshaving a larger diameter to minimize flow restrictions in the fluid flowdirection. With reference to FIG. 10, spacer 320 comprises firststraight, larger diameter wires e.g. 331 and 332, which are themselvesthe spacers. First wires 331, 332 are separated at intervals by adistance “x” and are braced and laterally spaced at equal intervals ofdistance “y” by a pair 333 of second wires 334 and 335 of preferablysmaller diameter. The distance “x” is greater than the ribbon width “w”by a distance “g” which defines a gap 336 between adjacent ribbons alongthe flow path. The distance “g” is slightly more than twice the diameterof the second wires 334 and 335, so as to provide a free gap for thesecond wires to wrap around the first wires 331 without interferencewith the adsorbent ribbons. This gap 336 between each pair of ribbonsalso provides ventilation between all the flow channels for pressureequalization and flow redistribution to minimize channeling in the eventof any flow maldistribution or tolerance deviations.

IX. Adsorber Elements

[0180] Laminate sheets may be coupled together to form adsorberelements. Disclosed embodiments have used adhesives to bond laminatesheets together. In some embodiments, the adhesive is a ceramicmaterial, such as the same material used to produce the spacers in orderto withstand subsequent high temperature operations. In such anembodiment, the ceramic material may be diluted to form the adhesivematerial. The adhesive may be applied to the tops of the spacers or to alaminate sheet, such as a second surface of a laminate sheet. If theadhesive is applied to the tops of the spacers, the adhesive may beapplied to all of the spacers, or a suitable portion of the spacers. Ifadhesive is applied to a portion of the spacers, the adhesive may beapplied in a random or ordered manner to a certain portion of spacers.The portion of spacers to which adhesive is applied may depend onseveral factors, such as the type and bonding strength of the adhesiveused, the number of spacers on the laminate sheet, and the size andsurface area of the spacers. If adhesive is applied to the secondsurface of an adjacent laminate sheet, the entire surface area of thesheet, or only some portion of that surface area, may be coated withadhesive.

[0181] Laminate sheets do not have to be bonded together usingadhesives. For example, both metal mesh and spirally wound laminates mayheld in place by compressive force.

[0182] An adsorber element may be formed from any number of laminates,such as sheets. For example, stacked adsorber elements typically havefrom about 2 to about 5000 sheets, and more typically from about 50 toabout 500 sheets. The sheets may be bonded to each other sequentially(i.e., the first and second sheets are bonded together to form astructure and each additional sheet is added to the structureindividually) or in a group. For example, several sheets may be placedadjacent to each other and bonded together at the same time.Additionally, two or more groups of laminate sheets may be bondedtogether to form the adsorber element.

[0183] An exemplary adsorber element may be formed from individuallaminate sheets coupled together to form a stack of sheets. Thisadsorber element, or brick, may be altered or machined to conform to therequirements of the end use. For example, the brick may be cut intosmaller segments of any size or geometric shape. Additionally, the brickor segments may be molded.

[0184] Planar adsorbent layers can be formed as described above, eitheras individual, presized sheets, or capable of being cut to desired sizesand shapes. Alternatively, the adsorbent layer may be formed on acontinuous sheet. Using these disclosed embodiments, various differentgeometries and adsorber elements can be made.

[0185] For example, FIG. 13A shows a cylindrical or round mold 200 aboutwhich, or on which, plural adsorbent sheets 202 a-202 c spaced byspacers 204 are molded. Molds of other shapes may be used, such assquare, triangular, octagonal, oval, waveform, or other desiredgeometric shapes. A first such adsorbent sheet 202 a having spacers 204is placed adjacent an exterior surface 206 of the mold 200. Adhesivematerial is applied to all or a portion of the spacers, or on a secondadsorbent sheet 202 b. The second adsorbent sheet 202 b is placed aboutthe mold 200 and on top of the spacers 204 of the first adsorbent sheet202 a. This process is continued to provide as many adsorbent sheetlayers as desired. An additional adsorbent sheet 207 with or withoutspacers 204 (FIG. 13B) may be placed about the mold on top of the entirestructure. An adsorber element 208 can be formed as illustrated in FIG.13B by placing all desired adsorbent layers in position about the moldand curing the entire structure, or serially after every layer is addedto the structure, or intermittently after two or more layers are addedto the structure. The setting and/or curing step may be conducted usingheat.

[0186] Spiral adsorbent elements also can be formed, as illustrated inFIG. 14A. The disclosed spiral embodiment 400 was formed by spirallywinding a continuous sheet 410 of support material coated with adsorbentmaterial and having plural spacers 202 positioned thereon. Adhesivematerial is placed on some or all of the spacers 202, or alternativelyon the sheet material 410, prior to winding the continuous sheet, andthe adhesive cured. Once the spirally configured adsorber element isformed, the spacers within the structure typically are aligned one ontop of another, separated by support material, on a line bisectingadjacent spirals from an exterior surface to the core. Other spacerconfigurations on adjacent windings also may be possible, such as pluralspacers of a first winding being offset from the spacers on adjacentwindings, or plural spacers forming selected spacer patterns when viewedin cross section through the spirally configured adsorber element.

[0187] Once a spirally configured adsorber element is formed, it thencan be used by itself, it can be stacked with other adsorber elements,or it can be used to form separate, multisegmented, spirally woundmicroadsorbers. The spiral configuration also can be cut into otherdesired geometries, such as illustrated in FIG. 14B. The same effect canbe accomplished by placing flow barriers on the support material. Thebarrier material can be the same material that is used to form thesupports and/or the adhesive. To form the barriers, ceramic or othermaterial is deposited on a line transverse to the machine direction as acontinuous sheet is wrapped.

[0188] Spirally wound laminates as illustrated in FIGS. 14A and 14Btypically are contained in containment chambers, such as containmentchamber 412 illustrated in FIG. 14C in cross section. FIG. 14Cillustrates a laminate 414 wound about a mandrel 416. Workingembodiments of spirally wound laminates have been used withoutconstraining the mandrel 416 from movement as a result of differentialpressures applied to first and second ends of the laminate. The resulthas been mechanical degradation of the laminate, such as by abrasion ofadsorbent material from the support. Mechanical degradation has beensubstantially eliminated by constraining movement of the mandrel 416with the containment chamber as described with further reference toFIGS. 14C and 14D.

[0189] Working embodiments of the illustrated containment chamber 412and mandrel 416 were made from stainless steel, but could be made fromadditional materials, particularly metals and metal alloys, butadditional such materials as ceramics and polymeric materials. Theadsorbent material used to form the laminate 414 typically are activatedsubsequent to insertion into the containment chamber 412. In such cases,both the containment chamber 412 and the mandrel 416 must besufficiently robust to withstand the adsorbent activation temperature,such as temperatures of about 250° C. and greater. For adsorbentmaterials that can be activated at lower temperatures, the material usedto form the containment chamber 412 and mandrel 416 may be other thanmetals, metal alloys, ceramics, etc.

[0190]FIG. 14C further illustrates the use of a spider 418, shown indetail in FIG. 14D. With reference to FIG. 14D, the spider 418 is aunitary device, again typically made of metal or metal alloys, such asstainless steel, having an outer ring 420 an inner ring 422 and pluralspokes 424. Spokes 424 define plural flow through channels 426.Proceeding from a left side, FIG. 14C shows that the assembled laminatecontainment chamber 412 also includes a wire retainer disk 428 and afilter 430, such as a metal mesh filter. A fastener, such as bolt 432,is used to couple the spider 418, a wire retainer disk 428 and filter430 to the mandrel 416. Retainer disk 428 and filter 430 are optional,and the spider 418 can be used alone. The illustrated embodimentincludes a threaded mandrel 416, which receives bolt 432 to secure thesecomponents to the mandrel. In the illustrated embodiment, both ends ofthe containment chamber 412 are identically configured to have spiders418, wire retainer disks 428 and filters 430. Alternatively, a singlespider could be used on one end of the device, or plural spirally woundlaminates could be contained in a containment chamber with one or morespiders being located between the spirally wound laminates to preventaxial movement. As still another embodiment, a spirally wound laminateor laminates could be placed into a containment chamber, and then asubstantially uniform concentric compressive force applied to thecontainment chamber to deform it about the laminate or laminates toprevent axial movement of windings. To further prevent movement of thelaminate and to prevent gas flow out of the containment chamber 412, abead of material (not illustrated), such as a ceramic material, may beplaced about the inner circumference of the containment chamber. Othermethods of fastening can be used, such as a shoulder built into chamber412 (not illustrated). The filter rings 428 then contact this bead whenthe containment chamber is assembled.

[0191] Persons of ordinary skill in the art will realize that differentcontainment methods can be used in combination with spirally woundlaminates. For example, differently configured spiders can be used. Anysuch structure which supports a spiral laminate and mandrel to preventrelative axial movement of one and preferably both, and which allows forfluid flow distribution throughout the laminate, is suitable.

[0192]FIGS. 15A and 15B show still another embodiment 450 of an adsorberelement that can be formed by positioning plural laminate sheets 452a-452 e adjacent one another in a stack. Each of the sheets 452 includesplural spacers 454 adhered to a surface thereof. In contrast to otherdisclosed embodiments however, the spacers 454 do not have a uniformheight. Instead, the spacer height increases from a first end 456 of asheet 452 to a second end 458 of the sheet. Plural such sheets 452 arethen stacked and bonded as with other disclosed embodiments, i.e., byplacing adhesive on some or all of the spacers 454, or by placingadhesive on some or all of a portion of the bottom surface of the sheets452. The stack is then bonded together to form a radially extendingadsorber element as illustrated in FIG. 15B (spacers not shown). Feedgas typically is introduced into the PSA device housing the adsorberelement to the adsorbent layers adjacent the second and of the supportlayers, i.e., that region where the spacers have the greatest height.Product is then withdrawn from the first end.

[0193] In some applications, such as reactor or PSA apparatuses placedon board a vehicle, vibration and shock loadings are much more frequentand severe than in stationary commercial applications. The use oflaminates and spacers provide a structure that is more robust than abeaded or pelletized packed adsorber, and hence, provide additionalbenefits beyond size, weight, cost and pressure drop.

X. Ventilation Aperatures

[0194]FIGS. 16 and 17 illustrate an adsorber element 500 comprising aplurality of laminates 502. Laminates 502 are separated, such as byspacers (not shown), to form flow channels 504 between adjacentlaminates. Defined in adsorber element 500 are plural ventilationapertures 506 that permit fluid communication between flow channels 504.As a gas mixture is caused to flow through flow channels 504 in eitherthe X or Y direction, at least a portion of the gas mixture may flowthrough ventilation apertures 506 in the Z direction if there is apressure or concentration differential across the flow channels. Suchflow in the Z direction enhances flow mixing and equalizes pressure,constituent concentration, and flow fronts through the adsorber element500. It has been found that an adsorbent structure having ventilationapertures that allow gas flow between flow channels results in increasedproductivity and recovery in gas adsorption separation compared to anadsorbent structure without such apertures. Ventilation apertures can berandom or aligned in a particular direction, such as the Z direction, orstaggered. In working embodiments, apertures aligned in the Z directionprovide significantly improved results relative to embodiments withoutventilation apertures.

[0195] The amount of ventilation apertures used for a particularembodiment can be stated with reference to the amount of surface area ofa particular structure that is ventilation apertures. Ventilationapertures likely are only required because the physical structure of anadsorber element is not sufficiently controlled to prevent pressure andconcentration differences to occur. In a perfect system, no ventilationapertures would be used, and hence the ventilation aperture area wouldbe 0%. However, perfect systems are not readily achieved, if at all.Ventilation apertures are used to reduce the process requirements ofsubstantially identical channels. As a result, the total area ofapertures 506 for certain disclosed embodiments was desirably about 1percent to about 3 percent of the total area of a laminate. Theapertures may be equally spaced and aligned in the X and Y direction, oralternatively, the apertures 506 may be arranged in a staggered pattern.It also should be understood that there is no requirement as to thearrangement of apertures 506.

[0196] The apertures 506 may be formed in the laminate 502 by anysuitable method. For example, apertures 506 may be formed by drilling orpunching holes into the laminate 502. Alternatively, where a laminate502 is formed by applying a slurry of adsorbent material to a support,apertures 506 may be formed by blowing holes through the adsorbent sheetwith compressed fluid. Templates can be used to form the apertures.

[0197] Two or more separate adsorber elements can be positioned toprovide adsorber elements in series along a flow path.

XI. Activating Laminates and/or Adsorber Elements

[0198] Laminates and adsorber elements produced as described above mayneed to undergo additional processing prior to use. For example, thelaminates may be heated to volatilize nonessential volatile materials.Examples of heating methods include convection, induction, microwaves,IR, vacuum assisted heating, etc. Continuous processes have beendeveloped whereby a continuous sheet of material is transported througha continuous oven. The laminate may be subjected to a ramped heatingschedule to avoid thermal damage by vaporized nonessential materials.Often, using a purge gas to transport materials as they are releasedfrom the adsorbent materials also facilitates the process.

XII. EXAMPLES

[0199] The following examples are provided to exemplify certain featuresof working embodiments of the present invention. The scope of thepresent invention should not be limited to those features exemplified.

Example 1

[0200] This example concerns the effects that ventilation apertures haveon laminates made according to the present invention. Apertures wereformed in laminates made as described herein. The overall area of theapertures is expressed as a percentage of the area of the laminate.These laminates were tested in a reciprocating PSA apparatus andcompared to intact laminates, i.e., laminates without apertures, underthe same operating conditions, such as feed and exhaust pressures. Theresults are discussed below.

[0201]FIG. 18 is a schematic drawing of one example of a template usedto make the apertured laminates discussed below.

[0202] Tables 3 (control) and 4 (laminates with apertures) present dataconcerning recovery (%) versus normalized productivity(volume/volume/hour) at 90% oxygen purity and compares the results ofrectangular laminates made as described herein having ventilationapertures made by blowing holes through the laminate with compressed airversus laminates without ventilation apertures. The control had aspacer/substrate thickness of 0.66, whereas the spacer/substratethickness of the apertured laminate was about 0.68. Tables 3 and 4 showthat the productivity at a particular recovery was increased forapertured sheets versus adsorbent sheets without ventilation apertures.TABLE 3 Control Without Apertures RECOVERY FRACTIONAL CPM (%)PRODUCTIVITY 30 63.2 0.45 125 41.3 1.00

[0203] TABLE 4 Laminate With Apertures RECOVERY FRACTIONAL CPM (%)PRODUCTIVITY 30 66.8 0.48 125 41.3 1.00

[0204] Tables 5-7 provide data for recovery versus productivity at 90%oxygen purity for rectangular laminates having random and alignedventilation apertures made by blowing holes through the laminates withcompressed air compared to a control without ventilation apertures. Thelaminates with apertures had a total ventilation aperture area of about0.99%. Tables 5-7 indicate that ventilation apertures aligned in the Zdirection significantly improve the recovery and productivity relativeto a control at the same cycles per minute. TABLE 5 Control With NoApertures RECOVERY FRACTIONAL CPM (%) PRODUCTIVITY 30 70.5 0.487 12539.4 .999

[0205] TABLE 6 Laminate With Random Apertures RECOVERY FRACTIONAL CPM(%) PRODUCTIVITY 30 69.3 0.476 125 40.3 .984

[0206] TABLE 7 Laminate with Apertures Aligned in Z Direction RECOVERYFRACTIONAL CPM (%) PRODUCTIVITY 30 73.1 0.461 125 45.1 1.00

[0207] Tables 8-10 provide performance data at 90% oxygen purity forheavily loaded fibre glass laminates having ventilation apertures thatwere either aligned in the z direction and staggered in the y directionor aligned in both the z and y directions compared to a control withoutventilation apertures. The laminates with apertures had a totalventilation aperture area of about 0.97%. Tables 8-10 show that theproductivity at a particular recovery was decreased for laminates havingapertures versus laminates without ventilation apertures. TABLE 8Control With No Apertures RECOVERY FRACTIONAL CPM (%) PRODUCTIVITY 3058.5 0.662 125 34.6 1.00

[0208] TABLE 9 Laminate With Apertures Aligned in V Direction RECOVERYFRACTIONAL CPM (%) PRODUCTIVITY 30 58.8 0.663 125 33.9 .943

[0209] TABLE 10 Laminate with Apertures Staggered in Y DirectionRECOVERY FRACTIONAL CPM (%) PRODUCTIVITY 30 58.0 0.647 125 34.1 .959

[0210] Tables 11-15 provide performance data at 90% oxygen purity forfibre glass laminates having ventilation apertures compared to a controlwithout ventilation apertures. The laminates with ventilation apertureswere stacked in four different ways, z direction aligned, z directionstaggered, z direction aligned with every other laminates withoutventilation apertures, and z direction staggered with every otherlaminate without ventilation apertures.

[0211] Tables 11-15 provide data for recovery versus productivity forthe aforementioned laminates with ventilation apertures compared to acontrol without ventilation apertures. Tables 11-15 show that theproductivity at a particular recovery was decreased for laminates withapertures that were aligned in the z direction and were interspersedwith every other sheet being a sheet without ventilation apertures. Theother laminate combinations had increased productivity at a particularrecovery versus laminates without ventilation apertures.

[0212] Similar trends are seen at 70% oxygen purity. TABLE 11 ControlWith No Aperatures RECOVERY FRACTIONAL CPM (%) PRODUCTIVITY 30 69.70.635 90 60.3 .981

[0213] TABLE 12 Laminate With Apertures Aligned in Z Direction RECOVERYFRACTIONAL CPM (%) PRODUCTIVITY 30 76.3 0.598 90 64.6 .931

[0214] TABLE 13 Laminate with Apertures Staggered in Z DirectionRECOVERY FRACTIONAL CPM (%) PRODUCTIVITY 30 78.8 0.572 90 65.4 .888

[0215] TABLE 14 Laminate With Interspersed Apersed Apertures Aligned inZ Direction RECOVERY FRACTIONAL CPM (%) PRODUCTIVITY 30 70.3 0.652 9059.7 .983

[0216] TABLE 15 Laminate with Interspersed Apertures Staggered in ZDirection RECOVERY FRACTIONAL CPM (%) PRODUCTIVITY 30 69.2 0.657 90 60.01.000

Example 2

[0217] This example concerns an adsorbent laminate and the resultsobtained using such pack as provided below in Table 16. A rectangularadsorbent pack was made using methods as described herein. Therectangular pack included activated alumina dessicant and alithium-exchanged zeolite applied to a fiber glass substrate. Incontrast to Example 1, printed spacers having a height of 125micrometers were used instead of metal mesh spacers. This pack wastested as a single pack on a stationary bed, rotary valve testingapparatus with a feed pressure of between about 3 and 11 psig operatingat the cycle speeds stated in Table 16. TABLE 16 CPM O₂ Purity (%)Recovery (%) Productivity (v/v hour) 30 90 38.2 773 148 90 34.7 1943

[0218] The rectangular pack of this example experienced about half thepressure drop compared to other laminate configurations. Moreover, usingprinted spacers instead of wire mesh spacers decreases the weight of thepack and provides a significant cost decrease. Printed spacers alsoallow the formation of bonded packs instead of non-bonded packs madeusing metal mesh spacers. Bonded packs can be formed, and then cut intoany desired shape, and also are easier to manipulate compared tononbonded packs.

Example 3

[0219] This example concerns an adsorbent laminate and the resultsobtained using such pack for hydrogen purification as presented in Table17. A spirally wound adsorbent pack was made using methods describedherein. The spirally wound pack included activated alumina (AA), 3Xzeolite, and SZ5 zeolite. Both a mesh substrate and mesh spacers wereused to make the pack. An apparatus having 8 beds of this spirally woundpack were then tested simultaneously on a rotary bed testing apparatuscapable of providing light product reflux. The feed pressure was about100 psig. The results of this study using a feed gas composition ofsyngas having about 75% H₂ are provided below in Table 17. Standardindustry performance has recovery values of between approximately 75% toabout 85%, with productivity values of approximately 150 v/v-hour. TABLE17 CPM H₂ (cycles per Purity CO Concentration Recovery Productivityminute) (%) (PPM) (%) (v/v.hour) 30 99.9 100 69.4 3982 81 99 100 58.59273

[0220] Examples 1-3 illustrate that packs of various geometricconfigurations can be made, including without limitation, trapezoidal,rectangular and spirally wound structures. Various substrates, forexample fiber glass and metal materials, can be used, to which anadsorbent or adsorbents and/or desiccants can be applied to form thelaminates. Spacers can be made using a variety of methods, includingmetal mesh spacers, and printed spacers, and pack performancemaintained. Such packs can be used for various gas separationprocedures, such as oxygen and hydrogen purification. Packs can bemanufactured primarily for use at relatively low pressures, such as thedescribed trapezoidal and rectangular packs, or for high pressureapplications, such as the spirally wound pack described in Example 3,which are contained within a casing allowing for higher pressureapplications. Any of the described packs can be used alone, or incombination with multiple packs, either of the same configuration or ofdiffering configurations, or can be used for ambient or relatively lowtemperatures, or at relatively high temperatures.

XIII. Exemplary PSA Apparatuses

[0221] The laminates/adsorber elements described herein can be usedadvantageously with pressure swing adsorption devices. An example of asuitable PSA device is illustrated in FIGS. 26-30. FIG. 19 shows arotary PSA module 600, particularly suitable for smaller scale oxygengeneration. Module 600 includes a number “N” of adsorber elements 602 inan adsorber housing body 604.

[0222] Each adsorber element 602 has a first end 606 and a second end608, with a flow path there between contacting an adsorbent, such as anitrogen-selective adsorbent. The adsorber elements 602 are deployed inan axisymmetric array about axis 607 of the adsorber housing body. Thehousing body 604 is capable of relative rotary motion about axis 607with first and second functional bodies 608 and 609, being engagedacross a first valve face 610 with the first functional body 608 towhich feed air is supplied and from which nitrogen-enriched air iswithdrawn as the heavy product, and across a second valve face 611 withthe second functional body 609 from which oxygen-enriched air iswithdrawn as the light product.

[0223] In disclosed embodiments depicted in FIGS. 19-25, the adsorberhousing 604 rotates and shall henceforth be referred to as the adsorberrotor 604, while the first and second functional bodies are stationaryand together constitute a stator assembly 612 of the module. The firstfunctional body shall henceforth be referred to as the first valvestator 608, and the second functional body shall henceforth be referredto as the second valve stator 609.

[0224] In the embodiment shown in FIGS. 19-25, the flow path through theadsorber elements is parallel to axis 607, so that the flow direction isaxial. The first and second valve faces are shown as flat annular discsnormal to axis 607. More generally the flow direction in the adsorberelements 603 may be axial or radial, and the first and second valvefaces may be any figure of revolution centred on axis 607. The steps ofthe process and the functional compartments to be defined will be in thesame angular relationship regardless of a radial or axial flow directionin the adsorbers.

[0225] FIGS. 20-25 are cross sections of module 601 in the planesdefined by arrows 612-613, 614-615, and 616-617. Arrow 620 in eachsection shows the direction of rotation of the rotor 604.

[0226]FIG. 20 shows section 612-613 of FIG. 19, which crosses theadsorber rotor. Here, “N”=72. The adsorber elements 603 are mountedbetween outer wall 621 and inner wall 622 of adsorber wheel 808. Eachadsorber comprises a rectangular flat pack 603 of adsorbent sheets 623,with spacers 624 between the sheets to define flow channels in the axialdirection. Separators 625 are provided between the adsorbers to fillvoid space and prevent leakage between the adsorbers. The adsorbentsheets comprise a reinforcement material as discussed herein. For airseparation to produce enriched oxygen, typical adsorbents are X, A orchabazite type zeolites, typically exchanged with lithium, calcium,strontium, magnesium and/or other cations, and with optimizedsilicon/aluminum ratios. The zeolite crystals are bound with silica,clay and other binders, or self-bound, within the adsorbent sheetmatrix.

[0227] For working embodiments sheet thicknesses have been about 150microns, with spacer heights in the range of from about 10 to about 300microns, more typically from about 75 to about 175 microns, and adsorberflow channel length approximately 20 cm. Using X type zeolites,excellent performance has been achieved in oxygen separation from air atPSA cycle frequencies in the range of 30 to 150 cycles per minute.

[0228]FIG. 21 shows the porting of rotor 604 in the first and secondvalve faces respectively in the planes defined by arrows 614-615, and616-617. An adsorber port 630 provides fluid communication directly fromthe first or second end of each adsorber to respectively the first orsecond valve face.

[0229]FIG. 22 shows the first stator valve face 700 of the first stator608 in the first valve face 610, in the plane defined by arrows 614-615.Fluid connections are shown to a feed compressor 701 inducting feed airfrom inlet filter 702, and to an exhauster 703 deliveringnitrogen-enriched second product to a second product delivery conduit704. Compressor 701 and exhauster 703 are shown coupled to a drive motor705.

[0230] Arrow 20 indicates the direction of rotation by the adsorberrotor. In the annular valve face between circumferential seals 706 and707, the open area of first stator valve face 700 ported to the feed andexhaust compartments is indicated by clear angular segments 711-716corresponding to the first functional ports communicating directly tofunctional compartments identified by the same reference numerals711-716. The substantially closed area of valve face 700 betweenfunctional compartments is indicated by hatched sectors 718 and 719,which are slippers with zero clearance, or preferably a narrow clearanceto reduce friction and wear without excessive leakage. Typical closedsector 718 provides a transition for an adsorber, between being open tocompartment 714 and open to compartment 715. A tapering clearancechannel between the slipper and the sealing face provides gradualopening, so as to achieve gentle pressure equalization of an adsorberbeing opened to a new compartment. Much wider closed sectors (e.g. 719)are provided to substantially close flow to or from one end of theadsorbers when pressurization or blowdown is being performed from theother end.

[0231] The feed compressor provides feed air to feed pressurizationcompartments 711 and 712, and to feed production compartment 713.Compartments 711 and 712 have successively increasing working pressures,while compartment 713 is at the higher working pressure of the PSAcycle. Compressor 701 may thus be a multistage or split streamcompressor system delivering the appropriate volume of feed flow to eachcompartment so as to achieve the pressurization of adsorbers through theintermediate pressure levels of compartments 711 and 712, and then thefinal pressurization and production through compartment 713. A splitstream compressor system may be provided in series as a multistagecompressor with interstage delivery ports; or as a plurality ofcompressors or compression cylinders in parallel, each delivering feedair to the working pressure of a compartment 711 to 713. Alternatively,compressor 701 may deliver all the feed air to the higher pressure, withthrottling of some of that air to supply feed pressurizationcompartments 711 and 712 at their respective intermediate pressures.

[0232] Similarly, exhauster 703 exhausts nitrogen-enriched heavy productgas from countercurrent blowdown compartments 714 and 715 at thesuccessively decreasing working pressures of those compartments, andfinally from exhaust compartment 716 which is at the lower pressure ofthe cycle. Similarly to compressor 701, exhauster 703 may be provided asa multistage or split stream machine, with stages in series or inparallel to accept each flow at the appropriate intermediate pressuredescending to the lower pressure.

[0233] In the example embodiment of FIG. 22, the lower pressure isambient pressure, so exhaust compartment 716 exhaust directly to heavyproduct delivery conduit 704. Exhauster 703 thus provides pressureletdown with energy recovery to assist motor 705 from thecountercurrrent blowdown compartments 714 and 715. For simplicity,exhauster 703 may be replaced by throttling orifices as countercurrentblowdown pressure letdown means from compartments 714 and 715.

[0234] In some preferred embodiments, the lower pressure of the PSAcycle is subatmospheric. Exhauster 703 is then provided as a vacuumpump, as shown in FIG. 23. Again, the vacuum pump may be multistage orsplit stream, with separate stages in series or in parallel, to acceptcountercurrent blowdown streams exiting their compartments at workingpressures greater than the lower pressure which is the deepest vacuumpressure. In FIG. 23, the early countercurrent blowdown stream fromcompartment 714 is released at ambient pressure directly to heavyproduct delivery conduit 704. If for simplicity a single stage vacuumpump were used, the countercurrent blowdown stream from compartment 715would be throttled down to the lower pressure over an orifice to jointhe stream from compartment 716 at the inlet of the vacuum pump.

[0235]FIGS. 24 and 25 show the second stator valve face, at section616-617 of FIG. 19. Open ports of the valve face are second valvefunction ports communicating directly to a light product deliverycompartment 721; a number of light reflux exit compartments 722, 723,724 and 725; and the same number of light reflux return compartments726, 727, 728 and 729 within the second stator. The second valvefunction ports are in the annular ring defined by circumferential seals731 and 732. Each pair of light reflux exit and return compartmentsprovides a stage of light reflux pressure letdown, respectively for thePSA process functions of supply to backfill, full or partial pressureequalization, and cocurrent blowdown to purge.

[0236] Illustrating the option of light reflux pressure letdown withenergy recovery, a split stream light reflux expander 740 is shown inFIGS. 19 and 24 to provide pressure letdown of four light reflux stageswith energy recovery. The light reflux expander provides pressureletdown for each of four light reflux stages, respectively between lightreflux exit and return compartments 722 and 729, 723 and 728, 724 and727, and 725 and 726 as illustrated. The light reflux expander 740 maypower a light product booster compressor 745 by drive shaft 846, whichdelivers the oxygen enriched light product to oxygen delivery conduit747 and compressed to a delivery pressure above the higher pressure ofthe PSA cycle. Illustrating the option of light reflux pressure letdownwith energy recovery, a split stream light reflux expander 240 isprovided to provide pressure letdown of four light reflux stages withenergy recovery. The light reflux expander serves as pressure letdownmeans for each of four light reflux stages, respectively between lightreflux exit and return compartments 722 and 729, 723 and 728, 724 and727, and 725 and 726 as illustrated.

[0237] Light reflux expander 840 is coupled to a light product pressurebooster compressor 845 by drive shaft 846. Compressor 845 receives thelight product from conduit 625, and delivers light product (compressedto a delivery pressure above the higher pressure of the PSA cycle) todelivery conduit 850. Since the light reflux and light product are bothenriched oxygen streams of approximately the same purity, expander 740and light product compressor 745 may be hermetically enclosed in asingle housing which may conveniently be integrated with the secondstator as shown in FIG. 19. This configuration of a “turbocompressor”oxygen booster without a separate drive motor is advantageous, as auseful pressure boost of the product oxygen can be achieved without anexternal motor and corresponding shaft seals, and can also be verycompact when designed to operate at very high shaft speeds.

[0238]FIG. 25 shows the simpler alternative of using a throttle orifice750 as the pressure letdown means for each of the light reflux stages.

[0239] With reference to FIG. 19, compressed feed air is supplied tocompartment 713 as indicated by arrow 725, while nitrogen enriched heavyproduct is exhausted from compartment 717 as indicated by arrow 726. Therotor is supported by bearing 760 with shaft seal 761 on rotor driveshaft 762 in the first stator 608, which is integrally assembled withthe first and second valve stators. The adsorber rotor is driven bymotor 763 as rotor drive means.

[0240] As leakage across outer circumferential seal 731 on the secondvalve face 611 may compromise enriched oxygen purity, and moreimportantly may allow ingress of atmospheric humidity into the secondends of the adsorbers which could deactivate the nitrogen-selectiveadsorbent, a buffer seal 770 is provided to provide more positivesealing of a buffer chamber 771 between seals 731 and 771. Even thoughthe working pressure in some zones of the second valve face may besubatmospheric (in the case that a vacuum pump is used as exhauster703), buffer chamber is filled with dry enriched oxygen product at abuffer pressure positively above ambient pressure. Hence, minor leakageof dry oxygen outward may take place, but humid air may not leak intothe buffer chamber. In order to further minimize leakage and to reduceseal frictional torque, buffer seal 771 seals on a sealing face 772 at amuch smaller diameter than the diameter of circumferential seal 731.Buffer seal 770 seals between a rotor extension 775 of adsorber rotor604 and the sealing face 772 on the second valve stator 609, with rotorextension 775 enveloping the rear portion of second valve stator 609 toform buffer chamber 771. A stator housing member 780 is provided asstructural connection between first valve stator 608 and second valvestator 609.

[0241]FIG. 27 depicts a stationary bed system, where the feed ends ofadsorbers 803 use a rotary valve to synchronize flows. The light productend uses some valve switching in order to affect a PSA process. Feed gasis transported via conduit 813 to heavies valve 867, through dynamicseal 860 and rotor body 861, rotating about axis 862 by motor 863. Feedflow is directed to seal 864 and through stator housing 865 to adsorber803. Exhaust gases are directed from adsorber 803 through stator housing865, seal 864, and rotor body 861. The fluids are contained by secondstator housing 866 in coordination with stator housing 865, andwithdrawn via conduit 817.

[0242] The light product end of the adsorbers 803 are depicted asconventional conduit with directional valves 868 used to providesynchronized pressure and flow cycling in coordination with the feed endvalve 867, and the adsorbers 803, with the product fluid being deliveredby product conduit 847. Note that this drawing depicts only the simplest2-adsorber PSA and that it represents all PSA configurations with arotary feed valve and conventional valve arrangements for the lightproduct end fluids. The light product end system is completely enclosedin an impermeable container 870, where tight fluid sealing is achievedacross the whole boundary. In this option, atmospheric bornecontaminants are not able to enter into the process across the valvestem actuators, which are the process containment seals. The staticbuffer space (the space around the valves bounded by static sealing) ispreferably filled with a buffer fluid, introduced by a buffer fluidsupply leading to port 871. A positive pressure gradient over theambient pressure is a preferred option. This buffer fluid is alsopreferably circulated and refreshed by allowing the fluid to bewithdrawn by port 872.

[0243] One way valve 869 can be used to minimize reverse flow of anycontaminant coming from down stream equipment or processes, as well asthe preferred option of using product gas as the buffer fluid by closingvalve 874 and allowing the product fluid to enter container 870 viavalve 873, and to allow the product to be withdrawn from the container873 through product conduit 875.

[0244]FIG. 28 also depicts a rotary PSA system, wherein the lightproduct end of adsorbers 803 uses a multi-port rotary distributor valveto synchronize pressure and flow cycles. The lights valve 878 contains arotor 879 being rotated by motor 880, and where dynamic seals 881communicate with the adsorbers 803 in a cyclic manner. Feed gas isallowed in conduit 813 to a set of directional valves 876, and is thendirected to one of the adsorbers 803, where product gas is drawn offthrough seal 881, through lights rotor 879, and into product conduit 847via dynamic seal 882 and product port 883. The dynamic seals 881 and 882are process containment seals, and in the configuration where lightsvalve housing 884 is not sealed, they are also the primary seal, andhave the least amount of resistance to contaminant ingress from thesurrounding atmosphere. In one option, the housing 884 can be sealed, inorder to create a static buffer space that can be protected as discussedabove. Another option is to allow the static buffer chamber to breathethrough breather 885 coupled to blanket gas supply 886. Anotherpreferred option is to allow the static buffer chamber to breathethrough breather 887, and preferably through guard trap 888. Exhaustgases are withdrawn from adsorber 803 via directional valve 876 andthrough conduit 817.

[0245] A combination of devices shown in FIGS. 27 and 28, such asheavies valve 867, coupled to adsorbers 803 and to lights valve 878 isalso considered a rotary PSA and is able to benefit from the invention.A system consisting of the light product end valves 868 with associatedconduits, along with adsorbers 803 and first end valves 878 andassociated conduits consist of conventional PSA, and can be seen to alsobenefit from the invention.

[0246] The present invention has been described with respect to certainembodiments. The scope of the invention should not be limited to thesedescribed embodiments, but rather should be determined by reference tothe following claims.

We claim:
 1. A method for making an adsorbent laminate for highfrequency PSA processes, comprising: forming a slurry comprising aliquid suspending agent, an adsorbent and a binder; making a laminate byapplying the slurry to support material or admixing support materialwith the slurry.
 2. The method according to claim 1 where the slurry isapplied to support material using electrophoretic deposition.
 3. Themethod according to claim 1 where the material is applied to supportmaterial, and further comprising: milling the slurry to form a milledslurry; and applying the milled slurry to support material.
 4. Themethod according to claim 3 where the slurry comprises: a zeolite; and acolloidal silica-based binder.
 5. The method according to claim 4 wherethe zeolite is selected from the group consisting of ion-exchanged X, Aor chabazite-type zeolites.
 6. The method according to claim 4 where thezeolite is a lithium exchanged zeolite.
 7. The method according to claim4 where the silica-based binder is Ludox HS 30 or Ludox HS40.
 8. Themethod according to claim 3 where the slurry further includes a loweralkyl alcohol.
 9. The method according to claim 8 where the lower alkylalcohol is isopropyl alcohol.
 10. The method according to claim 1 wheresupport material is admixed with the slurry, and the slurry furtherincludes a high-molecular-weight polyvinyl alcohol.
 11. The methodaccording to claim 3 where the slurry has an initial viscosity prior tomilling of greater than 200 cps, and a viscosity subsequent to millingof less than 150 cps.
 12. The method according to claim 1 where theadsorbent material is formed in situ.
 13. The method according to claim1 and further comprising firing the laminate to calcine the binder andactivate the adsorbent.
 14. The method according to claim 1 and furthercomprising forming spacers on the laminate.
 15. The method according toclaim 14 where spacer dimensions vary.
 16. The method according to claim14 where the laminate has a first end and a second end, and the spacerheight increases from the first end to the second end.
 17. The methodaccording to claim 1 and further comprising: forming plural laminates;forming at least one aperture in the laminates; and stacking theadsorbent bodies to form an adsorbent structure having a flow channelbetween adjacent bodies, whereby a portion of a gas flowing through theflow channels flows through the apertures to facilitate pressureequalization in the adsorbent structure.
 18. The method according toclaim 17 where at least a portion of the plural laminates includespacers.
 19. The method according to claim 1 where the slurry is appliedto only one surface of the support material.
 20. The method according toclaim 1 where the support material comprises two major planar surfaces,and slurry is applied to both planer surfaces.
 21. The method accordingto claim 1 where the slurry material is applied to the support materialusing a roll coater.
 22. The method according to claim 20 where the rollcoater is a split roll coater.
 23. The method according to claim 1 wherethe slurry is applied to support material, and the slurry compriseswater, isopropyl alcohol, Ludox, Odorlok, and zeolite.
 24. The methodaccording to claim 3 where the support material is selected from thegroup consisting of glass fibers, ceramic fibers, scrim, stainlesssteel, metal foil, metal mesh, carbon-fiber, cellulosic materials,polymeric materials, and combinations of these materials.
 25. The methodaccording to claim 1 where the support material is metal mesh, theslurry is applied to the metal mesh by electrophoretic deposition, andthe metal mesh is surface prepared prior to deposition of the slurrymaterial.
 26. The method according to claim 25 where the metal mesh issurface prepared by oxidation, anodization, texturing, and combinationsthereof.
 27. The method according to claim 1 where the slurry hassupport material admixed therewith and comprises colloidal silica,ceramic fiber, glass fiber and zeolite.
 28. The method according toclaim 27 and further comprising depositing the slurry onto a foraminouswire, draining the slurry material, and pressing the material to form aceramic adsorbent paper.
 29. The method according to claim 28 andfurther comprising applying a reactive binder to the slurry material onthe foraminous wire.
 30. The method according to claim 29 where thereactive binder is an alginate-based binder.
 31. The method according toclaim 1 where the slurry further comprises hydrated magnesium aluminumsilicates.
 32. The method according to claim 31 where the slurrycomprises attapulgite.
 33. A monolithic adsorbent laminate structurecomprising at least two laminates having an adsorbent material coatedthereon and including spacers on at least one surface of a laminate, atleast a portion of a laminate having ventilation apertures.
 34. Thestructure according to claim 33 where the spacers are formed from aceramic material.
 35. The structure according to claim 33 where thespacers have a height of from about 10 micrometers to about 300micrometers.
 36. The structure according to claim 33 where the spacershave a height of from about 75 micrometers to about 175 micrometers. 37.The structure according to claim 33 where the laminate sheet is madefrom a support material selected from the group consisting of glassfibers, milled glass fiber, glass fiber cloth, fiber glass, fiber glassscrim, ceramic fibers, stainless steel, metal foil, metal mesh,carbon-fiber, cellulosic materials, polymeric materials, andcombinations of these materials.
 38. The structure according to claim 33where the adsorbent material is a lithium exchanged zeolite.
 39. Thestructure according to claim 33 formed into various geometric patterns.40. The structure according to claim 33 where the spacers aresubstantially the same size.
 41. The structure according to claim 34where the spacers increase in height from a first end to a second end.42. An adsorber comprising a monolithic adsorbent structure comprisingplural laminates at least one sheet having an adsorbent material coatedthereon and including spacers on at least one surface, at least aportion of a laminate having flow-through apertures.
 43. The adsorberaccording to claim 42 comprising two or more monoliths stacked orotherwise configured in series along a gas flow path.
 44. The adsorberaccording to claim 42 comprising a rotary bed adsorber.
 45. A method formaking a monolithic adsorbent structure comprising: providing a supportsheet; substantially coating the support sheet with an adsorbentmaterial; forming plural spacers on the support sheet; and forming thesupport sheet with adsorbent material and spacers thereon into amonolithic structure.
 46. The method according to claim 45 andincluding: providing plural support sheets; coating the plural supportsheets with adsorbent material; forming spacers on at least a portion ofthe plural support sheets; placing an adhesive material on at least aportion of the spacers; stacking the plural support sheets and bondingthem to form a monolithic structure.
 47. The adsorber according to claim42 where the spacers are printed spacers having a predetermined geometryto provide a desired fluid flow path.